Composite iridium barrier structure with oxidized refractory metal companion barrier and method for same

ABSTRACT

An Ir—M—O composite film has been provided that is useful in forming an electrode of a ferroelectric capacitor, where M includes a variety of refractory metals. The Ir combination film effectively prevents oxygen diffusion, and is resistant to high temperature annealing in oxygen environments. When used with an underlying barrier layer made from oxidizing the same variety of M transition metals, the resulting conductive barrier also suppresses the diffusion of Ir into any underlying Si substrates. As a result, Ir silicide products are not formed, which degrade the electrode interface characteristics. The Ir combination film remains conductive, not peeling or forming hillocks, during high temperature annealing processes, even in oxygen. The Ir—M—O conductive electrode/barrier structures are useful in nonvolatile MFMIS (metal/ferro/metal/insulator/silicon) memory devices, DRAMs, capacitors, pyroelectric infrared sensors, optical displays, and piezoelectric transducers. A method for forming an Ir—M—O composite film barrier layer with an oxidized refractory metal barrier layer is also provided.

BACKGROUND AND SUMMARY OF THE INVENTION

[0001] The present invention is generally related to the fabrication ofintegrated circuits (ICs) and, more specifically, to the fabrication ofa highly stable conductive electrode barrier using an iridium (Ir)composite film with an adjacent barrier including an oxidizedtransition, or refractory metal.

[0002] Platinum (Pt) and other noble metals are used in IC ferroelectriccapacitors. The use of noble metals is motivated by their inherentchemical resistance. This property is especially desirable under hightemperature oxygen annealing conditions, such as those seen in thefabrication of ferroelectric capacitors. In addition, chemicalinteraction between noble metals and ferroelectric materials such asperovskite metal oxides, is negligible.

[0003] The above-mentioned noble metals are used as conductive electrodepairs separated by a ferroelectric material. One, or both of theelectrodes are often connected to transistor electrodes, or toelectrically conductive traces in the IC. As is well known, theseferroelectric devices can be polarized in accordance with the voltageapplied to the electrode, with the relationship between charge andvoltage expressed in a hysteresis loop. When used in memory devices, thepolarized ferroelectric device can be used to represent a “1” or a “0”.These memory devices are ferro-RAM (FeRAM) and metal ferroelectric metalinsulator silicon (MFMIS) transistors. Ferroelectric devices arenonvolatile. That is, the device remains polarized even after power isremoved from the IC in which the ferroelectric is imbedded.

[0004] There are problems in the use of metal, even noble metalelectrodes. Pt, perhaps the widely used noble metal, permits thediffusion of oxygen, especially during high temperature annealingprocesses. The diffusion of oxygen through Pt results in the oxidationof the neighboring barrier and substrate material. Typically, theneighboring substrate material is silicon or silicon dioxide. Oxidationcan result in poor adhesion between the Pt and neighboring layer.Oxidation can also interfere with the conductivity between neighboringsubstrate layers. Silicon substrates are especially susceptible toproblems occurring as a result of oxygen diffusion. The end result maybe a ferroelectric device with degraded memory properties. Alternately,the temperature of the IC annealing process must be limited to preventthe degradation of the ferroelectric device.

[0005] Various strategies have been attempted to improve theinterdiffusion, adhesion, and conductivity problems associated with theuse of noble metals as a conductive film in IC fabrication. Titanium(Ti), titanium oxide (TiO₂), and titanium nitride (TiN) layers have beeninterposed between a noble metal and silicon (Si) substrates to suppressthe interdiffusion of noble metal into Si, and to enhance adhesionbetween layers. However, Ti layers are generally only effective belowannealing temperatures of 600 degrees C. After a 600 degree C.annealing, Pt diffuses through the Ti layer to react with silicon,forming a silicide product. Further, the Pt cannot stop the oxygendiffusion. After a high temperature annealing, a thin layer of siliconoxide may be formed on the silicon surface, which insulates contactbetween silicon and the electrode.

[0006] Other problems associated with the annealing of a Pt metal filmare peeling and hillock formation. Both these problems are related tothe differences in thermal expansion and stress of Pt with neighboringIC layers during high temperature annealing. A layer of Ti overlying thePt film is known to reduce stress of the Pt film, suppressing hillockformation.

[0007] Ir has also been used in attempts to solve the oxygeninterdiffusion problem. Ir is chemically stable, having a high meltingtemperature. Compared to Pt, Ir is more resistant to oxygen diffusion.Further, even when oxidized, iridium oxide remains conductive. Whenlayered next to Ti, the Ir/Ti barrier is very impervious to oxygeninterdiffusion. However, Ir reacts with Ti. Like Pt, Ir is also veryreactive with silicon or silicon dioxide. Therefore, a bilayered Ir/Tior Ir/TiN barrier is not an ideal barrier metal.

[0008] Co-pending application Ser. No. 09/263,595, entitled “IridiumConductive Electrode/Barrier Structure and Method for Same”, invented byZhang et al., and filed on Mar. 5, 1999, discloses a multilayered Ir/Tafilm that is resistant to interdiffusion.

[0009] Co-pending application Ser. No. 09/263,970, entitled “IridiumComposite Barrier Structure and Method for Same”, invented by Zhang etal., and filed on Mar. 5, 1999, discloses a Ir composite film that isresistant to interdiffusion.

[0010] Co-pending application Ser. No. ______, entitled “CompositeIridium-Metal-Oxygen Barrier Structure with Refractory Metal CompanionBarrier and Method for Same”, invented by Zhang et al., and filed on May21, 1999, discloses a Ir composite film that is resistant tointerdiffusion.

[0011] It would be advantageous if alternate methods were developed forthe use of Ir as a conductor, conductive barrier, or electrode in ICfabrication. It would be advantageous if the Ir could be used withoutinteraction to an underlying Si substrate.

[0012] It would be advantageous if an Ir film could be altered withother conductive metals to improve interdiffusion properties. Further,it would be advantageous if this improved type of Ir film could belayered with an interposing film to prevent the interaction of Ir with asilicon substrate.

[0013] It would be advantageous if the barrier interposed between the Ircomposite film and the silicon substrate could be used as the gatedielectric of a transistor.

[0014] It would be advantageous if the above-mentioned Ir-metal filmcould resist the interdiffusion of oxygen at high annealingtemperatures. It would also be advantageous if the Ir-metal film was notsusceptible to peeling problems and hillock formation.

[0015] It would be advantageous if the Ir-metal film could be producedwhich remains electrically conductive after annealing at hightemperatures and oxygen ambient conditions.

[0016] Accordingly, a highly temperature stable conductive barrier layerfor use in an integrated circuit is provided. The barrier comprises anunderlying silicon substrate, a first barrier film including an oxidizedrefractory metal barrier overlying the substrate, and aniridium-refractory metal-oxygen (Ir—M—O) composite film overlying thefirst barrier film. The refractory metal is used to help stuff the grainboundaries of Ir polycrystals, improving structural stability.

[0017] Typically, the first barrier film is selected from the group ofmaterials consisting of TiO₂, Ta₂O₅, Nb₂O₅, ZrO₂, Al₂O₃, and HfO₂. Thefirst barrier layer has a thickness in the range of approximately 2 to100 nanometers (nm). The first barrier is used as a barrier to separatethe silicon substrate from the bottom electrode Ir composite film. Italso acts as a gate dielectric in a metal ferroelectric metal insulatorsilicon (MFMIS) memory.

[0018] The Ir—M—O composite film remains conductive after hightemperature annealing processes in an oxygen environment. Further, theIr—M composite film resists hillock formation, and resists peeling.Specifically, the Ir composite film includes the following materials:Ir—Ta—O, Ir—Ti—O, Ir—Nb—O, Ir—Al—O, Ir—Zr—O, and Ir—Hf—O. Typically, theIr—M—O composite film has a thickness in the range of approximately 10to 500 nm.

[0019] In some aspects of the invention, the barrier is used to form anelectrode in a ferroelectric device. Then, a ferroelectric film overliesthe Ir—M—O film. A conductive metal film made of a noble metal, theabove-mentioned Ir—M composite film, or multilayered conductive topelectrode overlies the ferroelectric film. The ferroelectric film iscapable of storing charges between the top and Ir—M—O electrodes.

[0020] Also provided is a method for forming a highly temperature stableconductive barrier overlying an integrated circuit substrate. The methodcomprising the steps of:

[0021] a) through PVD, CVD, or MOCVD processes, forming a first barrierlayer, as described above, overlying the substrate;

[0022] b) through PVD, CVD, and MOCVD processes, forming a firstcomposite film including iridium and oxygen, as described above,overlying the first barrier layer to a thickness in the range ofapproximately 10 to 500 nm; and

[0023] c) annealing the first composite film in an atmosphere selectedfrom the group of gases consisting of oxygen, N₂, Ar, and a vacuum, andin which the annealing temperature is in the range of approximately 400to 1000 degrees C., whereby the conductivity of the first composite filmis improved and the thickness of the first composite film is stabilized.

[0024] In some aspects of the invention, wherein a ferroelectriccapacitor is formed, a further step follows Step b), of:

[0025] d) depositing a ferroelectric material overlying the firstcomposite film; and

[0026] e) depositing a conductive top electrode overlying theferroelectric material, whereby a ferroelectric capacitor is formed. Asmentioned above, the disclosed Ir—M—O composite film is also suitable asthe top electrode.

[0027] Sputtering is one PVD process used to deposit the composite andbarrier films. When a four inch target is used, the first barriermaterial can be deposited by sputtering in Step a) at about 50 to 800watts (W), in an Ar—O₂ atmosphere at a pressure of 2-100 millitorr (mT).Step b) can include cosputtering Ir and a metal targets with a powerlevel in the range of approximately 50 to 800 watts. The metal targetsare selected from the group of metals consisting of Ta, Ti, Nb, Zr, Al,and Nf. The atmosphere is Ar—O₂ in a ratio in the range if approximately1:5 to 5:1, and the atmosphere pressure is in the range of approximately2 to 100 mT. Alternately, Step b) includes depositing the firstcomposite film through PVD deposition, sputtering with a single,composite source, in an oxygen environment. The single composite sourcematerial is selected from the group of materials consisting of Ir, Ta,Ti, Nb, Zr, Al, Hf, and oxides of the above-mentioned materials. Whenlarge targets are used, the sputtering power level for Steps a) and b)is about 2 to 20 kilowatts (kW).

[0028] In some aspects of the invention, the first barrier layer isformed in Step a) by depositing an oxidized refractory metal.Alternately, the refractory metal is deposited and, then, oxidizedbefore the deposition of the first composite film. In a thirdalternative, refractory metal is deposited with the first composite filmdeposited over the refractory metal. Then, the overlying film areannealed in an oxygen environment so that the refractory metal of thefirst barrier is oxidized.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIGS. 1-3 illustrate steps in a completed, highly temperaturestable conductive barrier layer, for use in an integrated circuit.

[0030]FIG. 4 is a flowchart illustrating steps in a method for forming ahighly temperature stable conductive barrier layer, such as used in aferroelectric capacitor.

[0031]FIG. 5 is a flowchart depicting steps in the formation of aferroelectric capacitor, using the conductive barrier Ir composite filmof the present invention.

[0032]FIG. 6 is scanning electron microscope (SEM) cross-section of apresent invention structure following annealing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0033] FIGS. 1-3 illustrate steps in a completed, highly temperaturestable conductive barrier layer, for use in an integrated circuit.Specifically, the conductive barrier is useful as an electrode in aferroelectric capacitor. FIG. 1 depicts conductive barrier 10 comprisinga substrate 12, a first barrier film 14, including material selectedfrom the group consisting of TiO₂, Ta₂O₅, Nb₂O₅, ZrO₂, Al₂O₃, and HfO₂,overlying substrate 12. A first composite film 16 including iridium andoxygen overlies first barrier film 14. First composite film 16 remainsconductive after high temperature annealing processes in an oxygenenvironment.

[0034] Substrate 12 is selected from the group of materials consistingof silicon, polysilicon, silicon dioxide, and silicon-germaniumcompounds, whereby first barrier layer 14 prevents the formation of Irsilicide products. First barrier layer 14 has a thickness 18 in therange of approximately 2 to 100 nanometers (nm).

[0035] Specifically, several types of first composite film 16 arepossible which include a transition metal, or refractory metal.Conductive barrier layer 10 includes first composite films 16 selectedfrom the group consisting of Ir—Ta—O, Ir—Ti—O, Ir—Nb—O, Ir—Al—O,Ir—Zr—O, and Ir—Hf—O. The conductivity of the electrode layers can bevaried by changing the relative composition ratio of metal, Ir, and O.Ir—M—O first composite film 16 has a thickness 20 in the range ofapproximately 10 to 500 nm. First composite film 16 and first barrierlayer 14 typically include common materials selected from the groupconsisting of Ti, Nb, Zr, Al, and Hf. That is, when first composite film16 includes Ti, first barrier layer 14 includes Ti. Likewise, when firstcomposite film 16 includes Nb, so does first barrier layer 14. Whenfirst composite film 16 includes Zr, so does first barrier layer 14.When first composite film 16 includes Al, so does first barrier film 14.When first composite film 16 includes Hf, so does first barrier film 14.Alternately, the metal in film 16 and barrier 14 are different. Forexample, a barrier layer 14 including Ti and a composite film 16 of Ta.

[0036]FIG. 2 illustrates conductive barrier layer 10 of FIG. 1 includedas part of a ferroelectric capacitor 40. Ferroelectric capacitor 40further includes a ferroelectric film 42 overlying first composite film16. A conductive metal film top electrode 44 overlies ferroelectric film42. In some aspects of the invention, top electrode 44 is the samematerial as first composite film bottom electrode 16. In this manner,ferroelectric film 42 is capable of storing charges, or maintainingpolarity, between top electrode 44 and bottom electrode 16. Topelectrode 44 is a noble metal, multilayered electrode, and one of theabove-mentioned Ir composite films 16, in alternative aspects of theinvention.

[0037] These structures include a conductive bottom electrode/barrierstructures on silicon, polysilicon or silicon dioxide substrate in thenonvolatile memories, such as MFMIS(metal/ferro/metal/insulator/silicon) memories, DRAM, capacitors,sensors, displays, and transducer applications.

[0038]FIG. 3 illustrates barrier structure 10 with a gate dielectric. Insome aspects of the invention when substrate 12 is silicon, structure 10further comprises a silicon dioxide layer 50 interposed betweensubstrate 12 and first barrier layer 14. Silicon dioxide layer 50improves the interface between substrate 12 and overlying metal barriers14 and 16.

[0039] The as-deposited Ir—M—O film 16 becomes most conductive with apost deposition annealing at 800-900° C. in O₂ ambient for 1-30 min.Thickness of the structure can be stabled by annealing at temperaturesof 600° C., or greater.

[0040] The symbol “/”, as used herein, defines a layering of films, sothat Ir/Ta is a layer of Ir film overlying a Ta film. The symbol “—”, asused herein, defines a combination or mixture of elements, so that aIr—Ta film is a composite film which includes elements of Ir and Ta.

[0041]FIG. 4 is a flowchart illustrating steps in a method for forming ahighly temperature stable conductive barrier layer, such as used in aferroelectric capacitor. Step 100 provides an integrated circuitsubstrate. The substrate is selected from the group of materialsconsisting of silicon, polysilicon, silicon dioxide, andsilicon-germanium compounds. In some aspects of the invention (notshown), a step follows Step 100, and precedes Step 102. Step 100 aincludes using a silicon substrate and forming a layer of silicondioxide over the silicon substrate having a thickness in the range ofapproximately 5 to 200 Å. The silicon dioxide layer improves theinterface between the silicon and a subsequently deposited metal oxidebarrier layer. The thickness of the silicon dioxide layer ranges fromabout 5 to 100 Å. The silicon dioxide layer permits the first barrierlayer formed in Step 102 to be used as a gate dielectric, such as usedin a MFMIS application. Alternative Step 100 a processes are discussedbelow.

[0042] Step 102 forms a first barrier layer including material selectedfrom the group consisting of TiO₂, Ta₂O₅, Nb₂O₅, ZrO₂, Al₂O₃, and HfO₂,overlying the substrate. Step 102 includes depositing the first barrierlayer through deposition methods selected from the group consisting ofCVD, PVD, and MOCVD. It is understood that PVD processes include both dcand RF (radio frequency) sputtering. In some aspects of the invention,Step 102 includes depositing the first barrier layer at approximatelyroom temperature. Step 102 also includes depositing the first barrierlayer to a thickness in the range of approximately 2 to 100 nm.

[0043] In some aspects of the invention, Step 102 includes depositing arefractory metal selected from the group consisting of Ta, Ti, Nb, Zr,and Hf. Then, in a step preceding Step 104 (not shown), the depositedmetal is annealed in an oxygen atmosphere, oxidizing the metal of thefirst barrier layer. The annealing temperature is about 400 to 1000degrees C., for a duration of about 1 to 120 minutes. Alternately, Step102 includes depositing a metal oxide selected from the group TiO₂,Ta₂O₅, Nb₂O₅, ZrO₂, Al₂O₃, and HfO₂. When the substrate is silicon, asilicon dioxide layer is formed simultaneously (Step 100 a) with Step102, due to the oxygen atmosphere. In another alternative, Step 102includes depositing a metal selected from the group consisting of Ta,Ti, Nb, Zr, and Hf. Step 102 includes a sub-step, following Step 104.Step 104 a (not shown) anneals the deposited first barrier layer metaland first composite film in an oxygen environment to oxidize the firstbarrier layer. Specifically, the annealing temperature is about 400 to1000 degrees C., for a duration of about 1 to 120 minutes. When thesubstrate is silicon, a silicon dioxide layer is formed simultaneously(Step 100 a) with the annealment of Step 104 a, due to the oxygenatmosphere.

[0044] Step 104 forms a first composite film of iridium and oxygen, withanother metal, overlying the first barrier layer. Step 104 includesdepositing the first composite film by deposition methods selected fromthe group consisting of PVD, CVD, and MOCVD. In some aspects of theinvention, Step 104 includes forming the first composite film atapproximately room temperature to a thickness in the range ofapproximately 10 to 500 nm. Step 104 includes the first composite filmbeing selected from the group consisting of Ir—Ta—O, Ir—Ti—O, Ir—Nb—O,Ir—Al—O, Ir—Zr—O, Ir—Hf—O. Step 106 is a product, where a multilayerstructure is formed that is resistive to interaction with the substrate.

[0045] Step 104 a includes annealing the first composite film to improvethe conductivity and to stabilize the first composite film thickness.The annealing is conducted in an atmosphere selected from the groupconsisting of N₂, O₂, Ar, and a vacuum, at an annealing temperature inthe range between approximately 400 and 1000 degrees C., for a durationof time in the range of approximately 1 to 120 minutes. That is, the Ta,Ti, Nb, Zr, or Hf metal deposited in Step 102 is oxidized in theannealing step of Step 104 a.

[0046] When sputtering is performed, Step 100 typically includesestablishing a base, pre-process, pressure in less than 1×10⁻⁵ and,preferably about 1×10⁻⁷ T. In some aspects of the invention, Step 102includes depositing the first barrier material by sputtering 4 inchtargets at approximately 50 to 800 watts, in an atmosphere including Arand O₂, at a pressure of about 2 to 100 mT. With larger targets, thepower levels are in the range of about 2 to 20 kW.

[0047] In some aspects of the invention, Step 104 includes depositingthe first composite film through PVD deposition. Specifically, dccosputtering is used with separate Ir and metal targets. The sputteringis conducted in an atmosphere of Ar—O₂ in a ratio in the range ofapproximately 1:5 to 5:1. The pressure varies from approximately 2 to100 mT. Separate Ir and metal oxide targets are RF sputtered, with themetal oxide target including a metal selected from the group consistingof Ta, Ti, Nb, Zr, Al, and Hf.

[0048] Further, Step 104 includes dc cosputtering separate Ir and metal4 inch targets at a power in the range of approximately 50 to 800 watts.The metal targets are selected from the group consisting of Ta, Ti, Nb,Zr, Al, and Hf In general, dc sputtering is used when the targets are aconductive material, and RF sputtering is used when one of the targetsis a nonconductive material. The above-mentioned power levels are usedwith 4 inch targets. When larger targets are used, such as an 11 or 13inch target, the sputtering power levels of Steps 102 and 104 are in therange of approximately 2 to 20 kW. Alternately, the power is expressedas a current density in the range of approximately 10 to 100 milliampsper square centimeter, at a few hundred volts.

[0049] Alternately, Step 104 includes depositing the first compositefilm through PVD deposition using sputtering with a single compositesource using a target of refractory metal material selected from thegroup consisting of Ir, Ta, Ti, Nb, Zr, Hf, and oxides of theabove-mentioned refractory metal materials. Typically, the sputtering isconducted in an oxygen atmosphere, although an oxygen atmosphere is lessimportant if the target material contains oxygen in the form of metaloxides.

[0050] In some aspects of the invention, Step 100 a includes forming theSiO₂ layer by depositing a refractory metal selected from the groupconsisting of Ta, Ti, Nb, Zr, Al, or Hf in Step 102 and performing anannealing step in an oxygen atmosphere following Step 102. Step 100 aoccurs simultaneously with the refractory metal annealing step.Alternately, a refractory metal oxide selected from the group TiO₂,Ta₂O₅, Nb₂O₅, ZrO₂, Al₂O₃, and HfO₂, is deposited in Step 102. Theoxygen atmosphere of the metal oxide deposition process simultaneouslycauses the Si substrate to oxidize in Step 100 a.

[0051]FIG. 5 is a flowchart depicting steps in the formation of aferroelectric capacitor, using the conductive barrier first compositefilm of the present invention. Steps 200 through 204 replicate Steps 100through 104 of FIG. 4. Step 206 deposits a ferroelectric materialoverlying the first composite layer. Step 208 forms a conductive metalfilm top electrode overlying the ferroelectric material. Step 210 is aproduct, where a ferroelectric capacitor is formed. When the topelectrode material is an Ir—M—O film as the first composite film, afurther step follows Step 208. Step 209 (not shown) anneals topelectrode composite film to improve the conductivity and to stabilizethe first composite film thickness. The annealing is conducted in anatmosphere selected from the group consisting of N2, O2, Ar, and avacuum, at an annealing temperature in the range between approximately400 and 1000 degrees C., for a duration of time in the range ofapproximately 1 to 120 minutes.

[0052]FIG. 6 is a scanning electron microscope (SEM) cross-section of apresent invention structure following annealing. A Ir—Ta—O/Ta—Ta₂O₅/SiO₂structure is shown after 800 degree C. annealing, for 90 minutes. Thepicture is presented to demonstrate the excellent film integrity.Further, the composite film remains conductive, with a sheet resistanceof about 25 ohms per square. In fact, the sheet resistance actuallydecreases as a result of annealing, from the pre-annealing value ofabout 60 ohms per square.

[0053] An Ir—M—O composite film has been provided that is useful informing an electrode of a ferroelectric capacitor. The composite filmincludes a variety of transition metal and oxygen, as well as iridium.The Ir—M—O composite film effectively resists oxygen diffusion to thesubstrate when a oxidized metal companion barrier is used, and isresistant to high temperature annealing in oxygen environments. Whenused with an underlying oxidized transition metal barrier layer, theresulting conductive barrier also suppresses to diffusion of Ir into anyunderlying Si substrates. As a result, Ir silicide products are notformed which degrade the electrode interface characteristics. The Ircomposite film remains conductive, and resists peeling and hillockformation during high temperature annealing processes, even in an oxygenatmosphere. The above-mentioned Ir composite film is useful in thefabrication of nonvolatile memories, such as metal ferroelectric metalinsulator silicon (MFMIS), DRAM, capacitors, pyroelectric infraredsensors, optical displays, and piezoelectric transducers. Additionally,the Ir composite film is useful in other high temperature oxidationenvironments. For example, in aerospace applications such a materialused in the fabrication of rocket thrusters. Other variations andembodiments will occur to those skilled in the art.

What is claimed is:
 1. In an integrated circuit, a highly temperaturestable conductive barrier comprising: a substrate; a first barrier film,including a material selected from the group consisting of TiO₂, Ta₂O₅,Nb₂O₅, ZrO₂, Al₂O₃, and HfO₂, overlying said substrate; a firstcomposite film including iridium and oxygen overlying said first barrierfilm; whereby said first composite film remains conductive after hightemperature annealing processes in an oxygen environment.
 2. Aconductive barrier as in claim 1 in which said substrate is selectedfrom the group of materials consisting of silicon, polysilicon, silicondioxide, and silicon-germanium compounds, whereby said first barrierlayer prevents the formation of Ir silicide products.
 3. A conductivebarrier as in claim 1 in which said first barrier layer has a thicknessin the range of approximately 2 to 100 nanometers (nm).
 4. A conductivebarrier as in claim 1 in which said first composite film is selectedfrom the Ir—Ta—O, Ir—Ti—O, Ir—Nb—O, Ir—Al—O, Ir—Zr—O, and Ir—Hf—O.
 5. Aconductive barrier as in claim 1 in which said first composite film andsaid first barrier layer include common material selected from a groupof materials consisting of Ti, Nb, Zr, Al, and Hf.
 6. A conductivebarrier as in claim 1 in which said first composite film has a thicknessin the range of approximately 10 to 500 nm.
 7. A conductive barrier asin claim 1, wherein a ferroelectric capacitor id formed, furthercomprising: a ferroelectric film overlying said first composite film;and a conductive metal film top electrode overlying said ferroelectricfilm, whereby a ferroelectric capacitor is formed, capable of storingcharges between said first and second films.
 8. A conductive barrier asin claim 7 in which said conductive metal film is an Ir and oxygencomposite film also including a metal selected from a group of materialsconsisting of Ta, Ti, Nb, Zr, Al, and Hf.
 9. A conductive barrier as inclaim 2 wherein said substrate is silicon and further comprising: asilicon dioxide layer interposed between said substrate and said firstbarrier layer, whereby said silicon dioxide layer improves the interfacebetween said substrate and overlying metal barriers.
 10. A method forforming a highly temperature stable conductive barrier overlying anintegrated circuit substrate, the method comprising the steps of: a)forming a first barrier layer, including TiO₂, Ta₂O₅, Nb₂O₅, ZrO₂, A₂O₃,and HfO₂, overlying the substrate; and b) forming a first composite filmincluding iridium and oxygen overlying the first barrier layer, wherebya multilayer structure is formed that is resistive to interaction withthe substrate.
 11. A method as in claim 10 in which Step b) includesforming the first composite film to a thickness in the range ofapproximately 10 to 500 nm.
 12. A method as in claim 10 in which Step a)includes depositing the first barrier layer through deposition methodsselected from the group consisting of PVD, CVD, and MOCVD.
 13. A methodas in claim 12 in which Step a) includes depositing the first barriermaterial by sputtering with a power in the range of approximately 2 to20 kilowatts (kW), in an Ar—O₂ atmosphere at a pressure of about 2 to100 millitorr (mT).
 14. A method as in claim 10 wherein a ferroelectriccapacitor is formed, including a further step, following Step b), of: d)depositing a ferroelectric material overlying the first composite film;and e) forming a conductive metal film top electrode overlying theferroelectric material, whereby a ferroelectric capacitor is formed. 15.A method as in claim 14 in which Step e) includes the conductive metalfilm being an Ir and oxygen composite film also including a metalselected from a group of materials consisting of Ta, Ti, Nb, Zr, Al, andHf.
 16. A method as in claim 10 in which Step b) includes the firstcomposite film being selected from the group of materials consisting ofIr—Ta—O, Ir—Ti—O, Ir—Nb—O, Ir—Al—O, Ir—Zr—O, and Ir—Hf—O.
 17. A methodas in claim 10 in which Step b) includes depositing the first compositefilm at approximately room temperature.
 18. A method as in claim 10 inwhich Step b) includes depositing the first composite film by depositionmethods selected from the group consisting of PVD, CVD, and MOCVD.
 19. Amethod as in claim 18 in which Step b) includes dc cosputtering separateIr and a metal targets with a power level in the range of approximately2 to 20 kW, in which the metal targets are selected from the group ofmetals consisting of Ta, Ti, Nb, Zr, Al, and Hf, in which the atmosphereis Ar—O₂ in a ratio in the range if approximately 1:5 to 5:1, and inwhich the atmosphere pressure is in the range of approximately 2 to 100mT.
 20. A method as in claim 18 in which Step b) includes depositing thefirst composite film through PVD deposition, sputtering with a single,composite source, in an oxygen environment.
 21. A method as in claim 20in which Step b) includes the single composite target refractory metalmaterial being selected from the group consisting of Ir, Ta, Ti, Nb, Zr,Al, Hf, and oxides of the above-mentioned refractory metal materials.22. A method as in claim 18 in which Step b) includes dc sputteringseparate Ir and metal targets including metal selected from the groupconsisting of Ta, Ti, Nb, Zr, Al, and Hf.
 23. A method as in claim 18 inwhich Step b) includes RF sputtering separate Ir and metal oxide targetsincluding metal selected from the group consisting of Ta, Ti, Nb, Zr,Al, and Hf.
 24. A method as in claim 10 including a further step,following Step b), of: c) annealing the first composite film, wherebythe conductivity of the first composite film is improved and thethickness of the first composite film is stabilized.
 25. A method as inclaim 24 in which Step c) includes annealing in an atmosphere selectedfrom the group of gases consisting of oxygen, N₂, Ar, and a vacuum, andin which the annealing temperature is in the range of approximately 400to 1000 degrees C., for a time duration in the range of approximately 1minute to 120 minutes.
 26. A method as in claim 24 in which Step c)includes annealing at a temperature in the range of approximately 800 to900 degrees C., for a duration of 1 to 30 minutes.
 27. A method as inclaim 10 wherein the substrate is selected from the group of materialsconsisting of silicon, polysilicon, silicon dioxide, andsilicon-germanium compounds.
 28. A method as in claim 27, wherein thesubstrate is silicon, and including a further step of: forming a layerof silicon dioxide overlying the substrate having a thickness in therange of approximately 5 to 200 Å, whereby the interface between thesubstrate and overlying layers of metal oxide are improved.
 29. A methodas in claim 28 in which Step a) includes depositing a refractory metalselected from the group consisting of Ta, Ti, Nb, Zr, and Hf, andincluding a further step, following Step a), of: a₂) forming the silicondioxide layer simultaneously with an annealment of the refractory metaldeposited in Step a) in an oxygen atmosphere, to form the metal oxidefirst barrier layer.
 30. A method as in claim 28 in which Step a)includes depositing a metal oxide selected from the group TiO₂, Ta₂O₅,Nb₂O₅, ZrO₂, Al₂O₃, and HfO₂, and in which the step of forming thesilicon dioxide layer occurs simultaneously with Step a).
 31. A methodas in claim 10 in which Step a) includes depositing the first barrierlayer at approximately room temperature.
 32. A method as in claim 10 inwhich Step a) includes the first barrier layer thickness being in therange of approximately 2 to 100 nm.
 33. A method as in claim 10 in whichStep a) includes depositing a metal selected from the group consistingof Ta, Ti, Nb, Zr, and Hf.
 34. A method as in claim 33 in which afurther step follows Step a), and precedes Step b), of: a₁) annealingthe deposited metal in an oxygen environment, at a temperature in therange of about 400 to 1000 degrees C., for a duration of about 1 to 120minutes, whereby the metal of the first barrier layer is oxidized.
 35. Amethod as in claim 10 in which Step a) includes depositing a metal oxideselected from the group TiO₂, Ta₂O₅, Nb₂O₅, ZrO₂, Al₂O₃, and HfO₂.